The Liberty Alliance is making heavy use of EPRs both in
message headers as well as in our Discovery Service
responses (used to describe how to invoke web services).
The current draft specifications are available at:
https://www.projectliberty.org/resources/specifications.php#box2
An interesting extension that we have done as well is defined
a new header for responses (EPRUpdate) to update the EPR that
was used to invoke the service (such as redirecting the request
to a different endpoint, adding additional reference parameters,
etc.) Details on that usage is within the SOAP Bindings
specification.
I believe this is a good example of a complete system
making concrete use of the WS-Addressing specifications.
Conor